A system of the kind described has been published in U.S. Pat. No. 4,884,194 (PHN 11.120) to the same assignee, herein incorporated by reference. According to the reference, in successive broadcast steps, (T+1) in number, successive versions of a particular message are broadcast from a source processor to more or less geometrically increasing numbers of further processors or modules. Especially for higher values of T, this leads to an enormous traffic on the intercommunication system.